WASHINGTON  Thousands of lawyers, election monitors and volunteers with video cameras will be mobilized on Election Day in an effort to guard against problems at the polls.

The Justice Department will dispatch more than 800 observers, a record for a non-presidential election year, to look for evidence of discrimination, intimidation and other obstacles to voter accessibility in at least 20 states.

The Democratic Party has a 50-state voter-protection effort and an estimated 7,000 lawyers at the ready. Liberal groups have set up hotlines for voters to call if they are denied the right to vote. And hundreds of people plan to film interviews at polling places where voters are being challenged that day.

Fueling the activity this year: dozens of close elections that could decide control of Congress and the potential for problems caused by electronic voting machines, statewide databases and identification requirements.

"There are going to be problems in every state," says Jon Greenbaum, director of the Voting Rights Project for the Lawyers' Committee for Civil Rights. The group is part of a coalition that has a toll-free hotline and lawyers poised in 23 states.

Republican and conservative interest groups are keeping a lower profile. The Republican National Committee is relying on its state parties for poll monitors and lawyers. Groups such as the Republican National Lawyers Association lack the manpower to match the NAACP, Common Cause and People for the American Way.

"Folks can game the system, and that's a concern," says Thor Hearne, general counsel for the American Center for Voting Rights, a conservative group. He calls candidates and local parties "the first line of defense."

Justice Department monitors will be deployed next week, partly based on close races for Congress and where questions have been raised about the integrity of the election process. That could include Baltimore, Chicago, Cleveland and other places that encountered problems during primaries this year.

Prosecutors will be on standby in each federal district across the country to pursue possible fraud cases or other election-related criminal activity. "Everyone agrees that we want to make voting easier and fraud harder," says Assistant Attorney General Wan Kim.

The effort by some liberal groups begins today with a series of public-service announcements by actors such as Ben Affleck and Jodie Foster.

•A consortium led by Common Cause plans to track voters' problems on a database and publicize them. In 2004, it received 55,000 complaints.

•The NAACP has hundreds of lawyers ready. "We're focusing more on how to redress problems when they occur," says the group's Dennis Hayes.

•Filmmaker Ian Inaba's volunteers hope to get aggrieved voters on the Internet via YouTube "while the polls are still open and the races are still alive."